1. Field of the Invention
The invention is directed to methods and materials useful in treating anatomical defects by employing tissue engineered structural support members and in particular to methods and materials useful in penile reconstruction.
2. Description of the Background
Conditions such as inadequate and ambiguous genitalia, caused by aphallia, rudimentary penis, severe hypospadias, traumatic injury or pseudohermaphroditism, require surgical intervention. Sex assignment in these patients is made after a thorough diagnostic evaluation and careful consultation with the family. The decision is made based on external genital morphology, hormonal sex and the established gender role. In numerous instances, a decision is made to rear the child as a female, regardless of the karyotype, due to surgical difficulties and poor results with phallic construction.
The penis consists of two parallel cylindrical bodies, the corpora cavemosa and beneath them the corpus spongiosum, through which the urethra passes. The urethra runs along the underside of the penis then rises to open at the expanded, cone-shaped tip, the glans penis, which fits like a cap over the end of the penis. Loose skin encloses the penis and also forms the retractable foreskin or prepuce. The root of the penis is attached to the descending portions of the pubic bone by the crura, the latter being the extremities of the corpora cavemosa.
There are many causes of impotence. Organic impotence is the loss of the ability to obtain or maintain a functional erection due to the interruption of certain physiologic processes. Causes of organic impotence include trauma such as spinal cord injury or pelvic fracture; postoperative complications such as prostatectomy, cystectomy, external sphincterotomy and abdominal perineal resection; vascular disease such as arteriosclerosis or priapism; neurologic disease such as peripheral neuropathy and multiple sclerosis; endocrinologic and metabolic disease such as diabetes, hypogonadism and renal failure; and medication such as estrogen, parasympatholytic, morphine, and heroin. The complex reflexes entailed in the mechanism of erection are also affected by physiological factors.
Phallic construction was initially attempted in the late 30""s using autogenous tissue (See e.g., Goodwin, W. E. et al., Phalloplasty. J. Urol., 68: 903, 1952). Rib cartilage had been used as a stiffener in patients with traumatic penile loss. This method involved multiple stage surgery which did not have a cosmetically satisfactory result (Frumpkin, A. P.: Am. Rev. Sov. Med., 2: 14, 1944). Silicone prostheses have become popularized in the 1970s (Bretan, P. N. Jr.: In: Genitourinary Prostheses. Montague, D. K. (ed), Philadelphia, W. B. Saunders Co., 1989; Small, M. P. et al., Urology, 5: 479, 1975). Although silicone penile prostheses are an accepted treatment modality for adults, complications such as erosion and infection remain a problem (Nukui, F. et al., Int. J. Urol., 4: 52, 1997; Kardar, A. et al., Scan. J. Urol. and Nephrol., 29: 355, 1995). Other problems reported with synthetic prostheses include extrusion through the urethra or sink of the dorsal penile shaft; lymphatic edema; irritation of the glans at the corona; slippage of the glans over the prosthesis; infection of the corpora cavernosa; crural perforation; midshaft septal perforation; and penile pain (Small, M. P. et al., Urology, 5: 479, 1975).
Although silicone penile prostheses are an accepted treatment modality for adults requiring penile reconstruction, its use has not been generally applied to the pediatric population, mainly due to the long-term problems associated with these artificial devices. Thus, there is a need for biocompatible and elastic penile implants that could be used in children who require genital reconstruction.
The present invention overcomes the problems and disadvantages associated with current strategies and designs in tissue and organ reconstruction reforming structural support members.
One embodiment of the invention is directed to an implantable structural member for use in treating a patient having an anatomical defect which is not caused by absent, damaged, or diseased cartilage. The defect is treated, at least in part, by providing structural support to adjacent tissue. The structural member is made from a polymeric matrix shaped in the form of the desired support member with dissociated cartilage-forming cells deposited on and in the matrix such that when the matrix is implanted, a cartilaginous structural member is formed. The cartilaginous structural member has controlled biomechanical properties to provide the required structural support in the area of the defect.
Another embodiment of the invention is directed to a method for treating a patient which has an anatomical defect not caused by absent, damaged or diseased cartilage. The defect is of a type that can be treated, at least in part, by providing structural support to adjacent tissue. The method involves providing a polymeric matrix shaped in the form of a desired support member. Dissociated cartilage forming cells are deposited on and in the matrix to form a matrix/cell construct. The matrix/cell construct is implanted in the patient at a site which needs structural support so that the construct forms a cartilaginous structural member with controlled biomechanical properties to provide the required structural support in the defect area.
A further embodiment of the invention is directed to a method for reconstructing the penis of a patient who needs such treatment. A biocompatible synthetic or natural polymeric matrix shaped to form a structural member and adopted to fit within the corpora cavemosa or to replace the corpora cavernosa is provided. Cartilage-forming cells is deposited on and in the polymeric matrix to form a matrix/cell construct. The matrix/cell construct is implanted into the corpora cavernosa of the patient so that a cartilaginous structural member is formed in vivo with controlled biomechanical properties thus providing the reconstructed penis with sufficient stiffness and bending strength to serve as a functional organ.
Other embodiments and advantages of the invention are set forth, in part, in the description which follows and, in part, will be obvious from this description and may be learned from the practice of the invention.